new RAII object for tempo map editing

gtk2_ardour/tempo_map_change.cc

@@ -0,0 +1,65 @@
+/*
+    Copyright (C) 2022 Paul Davis
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#include "pbd/i18n.h"
+#include "tempo_map_change.h"
+
+TempoMapChange::TempoMapChange (PublicEditor& e, std::string const & str, bool uoc, bool begin_now)
+	: editor (e)
+	, name (str)
+	, aborted (false)
+	, begun (false)
+	, update_on_commit (uoc)
+	, before (0)
+{
+	if (begin_now) {
+		begin ();
+	}
+}
+
+TempoMapChange::~TempoMapChange ()
+{
+	if (!aborted && begun) {
+		XMLNode& after = writable_map->get_state();
+		editor.session()->add_command (new Temporal::TempoCommand (_("tempo map change"), before, &after));
+
+
+		editor.commit_tempo_map_edit (writable_map, update_on_commit);
+		editor.commit_reversible_command ();
+	}
+}
+
+void
+TempoMapChange::begin ()
+{
+	writable_map = editor.begin_tempo_map_edit ();
+	before = &writable_map->get_state();
+	editor.begin_reversible_command (name);
+	begun = true;
+}
+
+void
+TempoMapChange::abort ()
+{
+	if (begun) {
+		editor.abort_tempo_map_edit ();
+		editor.abort_reversible_command ();
+		aborted = true;
+		begun = false;
+	}
+}

gtk2_ardour/tempo_map_change.h

@@ -0,0 +1,55 @@
+/*
+    Copyright (C) 2022 Paul Davis
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#include <string>
+
+#include "temporal/tempo.h"
+
+#include "public_editor.h"
+
+/* RAII for tempo map edits. This object manages both Tempo map RCU stuff, plus
+ * reversible command state, removing the need for repeated boilerplate at each
+ * map edit site.
+ *
+ * One complication: GUI tempo map markers are all reassociated with the
+ * relevant points of the write-copy of the map during ::begin() (typically
+ * called in the constructor, unless it's begin argument is false). You must
+ * delay getting a reference on a point to edit until after the TempoMapChange
+ * object has called begin() (i.e. has been constructed), otherwise the
+ * reference will point to the "old" copy of the map.
+ */
+
+class TempoMapChange {
+  public:
+	TempoMapChange (PublicEditor& e, std::string const & name, bool update_on_commit = true, bool begin = true);
+	~TempoMapChange ();
+
+	void begin ();
+	void abort ();
+
+	Temporal::TempoMap& map() const { return *writable_map.get(); }
+
+  private:
+	PublicEditor& editor;
+	Temporal::TempoMap::WritableSharedPtr writable_map;
+	std::string name;
+	bool aborted;
+	bool begun;
+	bool update_on_commit;
+	XMLNode* before;
+};